SAP Calculations | Part L Compliance

Scope and evidence

Built around planning, development and compliance decisions.

Use this page to understand when the service is usually needed, what evidence is reviewed and what information helps us quote accurately.

Planning and regulator context
Clear deliverables and next steps
Linked services considered early

The most efficient SAP work starts while the specification can still be adjusted. Fabric, glazing, thermal bridging, heating, ventilation and renewable systems all interact, so late changes can affect compliance.

When this service is used

Used for building regulations, new-build residential schemes, conversions and design-stage energy performance compliance.

Planning and project supportUsed for new dwellings, conversions and residential projects requiring Building Regulations energy-compliance evidence.

Risk and programme controlEarly assessment highlights where the design is close to a compliance threshold before procurement or construction makes changes expensive.

What the report normally includes

Design-stage SAP assessment
Part L compliance review
Fabric and services input review
Recommendations where compliance is not achieved
Final-stage support where required

What we need from you

Providing the right information at the start helps us confirm the scope, quote accurately and avoid back-and-forth once the work is underway.

Architectural plans and elevations
Construction specification
Heating and ventilation details
Window and door schedules
Number of plots or dwellings

SAP is a design process, not just a certificate at the end

Building energy assessment supporting SAP calculations and compliance. — Building performance assessment supporting energy-efficient design and compliance.

What a robust scope should cover

Geometry, floor areas, exposed elements and glazing
Wall, roof and floor constructions and insulation performance
Thermal-bridge assumptions and junction details
Heating, hot water, ventilation and control systems
Renewable technologies and low-carbon systems where proposed
Design-stage and as-built changes that affect the final calculation

What the work should leave you with

A clear view of whether the dwelling design meets the applicable energy requirements
Identification of the inputs driving performance
Practical options where the initial specification does not comply
A controlled route from design-stage assumptions to final as-built evidence

Why the detail mattersTreating SAP as part of design coordination gives the architect, M&E team and developer time to choose the most practical compliance route rather than correcting a completed building.

Useful to know before you enquire

Drawings alone are rarely enoughWe also need construction build-ups, heating and ventilation details, glazing performance and other specification information.

Design changes should be fed backChanges to insulation, windows, heating, ventilation or renewables can alter the result, so the calculation should follow the live specification.

Air tightness links into final performanceWhere an air permeability result is required, the tested value can affect the final energy calculation.

Plot types can be grouped carefullyFor larger schemes, repeated dwelling types can make the workflow more efficient, but orientation and specification differences still need to be captured.

FAQ

Common questions

When should SAP calculations start?

Ideally during design, once sufficient drawings and specification information are available but before key fabric and services choices are fixed.

Can you help if the design fails SAP?

Yes. We can identify the inputs driving the result and discuss practical specification changes for the design team to consider.

Do SAP calculations and EPCs use the same information?

They are linked on new dwellings, but the project still needs the correct assessment route and final as-built information before certification.

Related services

These services are often reviewed alongside SAP Calculations depending on the site, planning context and proposed development.

Structured enquiry

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Our custom enquiry builder asks service-specific questions so we can confirm the correct scope, identify linked services and avoid unnecessary delays.

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Submit site information, planning references and supporting documents once. We’ll review the scope and confirm what is required.

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